Reducing data transmissions in a virtual private network

ABSTRACT

A source node can append a unique identifier to an outbound client packet, transmit the outbound client packet to a recipient node via a port, and create a transmission record including: the unique identifier, a time stamp of the outbound client packet, and an identifier for the port. The source node can receive an inbound client packet that is appended with the unique identifier and a delta time indicating an amount of elapsed time between the recipient node receiving the outbound client packet and the recipient node transmitting the inbound client packet. The source node can determine a performance level of a VPN tunnel provided by the port based on the time stamp value of the outbound client packet, the delta time, and a time stamp value of the inbound client packet indicating a time at which the inbound client packet was received by the source node.

TECHNICAL FIELD

This disclosure relates in general to the field of computer networksand, more particularly, pertains to reducing data transmissions in avirtual private network.

BACKGROUND

A Virtual Private Network (VPN) can include thousands of computing nodesin network communication with each. The computing nodes can utilize VPNtunnels to transmit and receive data packets from one another.Currently, computing nodes in a VPN transmit a high number of packetsamongst each other. For example, data packets, such as HELLO ACKpackets, need to be periodically sent to keep channels open betweencomputing nodes. As another example, probe packets are regularly sent tomeasure performance characteristics of a VPN tunnel. In large VPNs, theload from transmitting the desired number of these data packets canoverload the router. One solution is to simply reduce the number ofHELLO ACK and probe packets that are transmitted between computingnodes, however this is not ideal for network performance. Accordingly,improvements are needed.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited features andother advantages of the disclosure can be obtained, a more particulardescription of the principles briefly described above will be renderedby reference to specific embodiments thereof which are illustrated inthe appended drawings. Understanding that these drawings depict onlyexemplary embodiments of the disclosure and are not therefore to beconsidered to be limiting its scope, the principles herein are describedand explained with additional specificity and detail through the use ofthe accompanying drawings in which:

FIG. 1 illustrates an example network device according to some aspectsof the subject technology;

FIGS. 2A and 2B illustrate an example system embodiments according tosome aspects of the subject technology;

FIG. 3 illustrates a schematic block diagram of an example architecturefor a network fabric;

FIG. 4 illustrates an example overlay network;

FIG. 5 illustrates a system for reducing data transmissions in a VPN;

FIG. 6 illustrates computing nodes appending client data packets tomeasure performance characteristics of a VPN tunnel; and

FIG. 7 illustrates an example method for reducing data transmissions ina virtual private network.

DESCRIPTION OF EXAMPLE EMBODIMENTS

The detailed description set forth below is intended as a description ofvarious configurations of the subject technology and is not intended torepresent the only configurations in which the subject technology can bepracticed. The appended drawings are incorporated herein and constitutea part of the detailed description. The detailed description includesspecific details for the purpose of providing a more thoroughunderstanding of the subject technology. However, it will be clear andapparent that the subject technology is not limited to the specificdetails set forth herein and may be practiced without these details. Insome instances, structures and components are shown in block diagramform in order to avoid obscuring the concepts of the subject technology.

Overview:

Disclosed are systems, methods, and computer-readable storage media forreducing data transmissions in a VPN. A source node can append a firstunique identifier to a first outbound client packet scheduled to betransmitted from the source node to a first recipient node. Afterappending the first unique identifier to the first outbound clientpacket, the source node can transmit the first outbound client packet tothe first recipient node via a first port of the source node, and createa first transmission record including the first unique identifier, atime stamp of the first outbound client packet, and an identifier forthe first port. The time stamp value of the first outbound client packetcan indicate a time at which the first outbound client packet wastransmitted by the source node to the first recipient node. The sourcenode can receive a first inbound client packet from the first recipientnode. The first inbound client packet can be appended with the firstunique identifier and a first delta time indicating an amount of elapsedtime between the first recipient node receiving the first outboundclient packet and the first recipient node transmitting the firstinbound client packet. The source node can determine a performance levelof a first Virtual Private Network (VPN) tunnel provided by the firstport based on the time stamp value of the first outbound client packet,the first delta time, and a time stamp value of the first inbound clientpacket. The time stamp value of the first inbound client packetindicates a time at which the first inbound client packet was receivedby the source node.

DETAILED DESCRIPTION

Disclosed are systems and methods for reducing data transmissions in aVPN. A brief introductory description of exemplary systems and networks,as illustrated in FIGS. 1 through 4, is disclosed herein, followed by adiscussion of reducing data transmissions in a VPN. The disclosure nowturns to FIG. 1.

A computer network is a geographically distributed collection of nodesinterconnected by communication links and segments for transporting databetween endpoints, such as personal computers and workstations. Manytypes of networks are available, with the types ranging from local areanetworks (LANs) and wide area networks (WANs) to overlay andsoftware-defined networks, such as virtual extensible local areanetworks (VXLANs).

LANs typically connect nodes over dedicated private communications linkslocated in the same general physical location, such as a building orcampus. WANs, on the other hand, typically connect geographicallydispersed nodes over long-distance communications links, such as commoncarrier telephone lines, optical lightpaths, synchronous opticalnetworks (SONET), or synchronous digital hierarchy (SDH) links. LANs andWANs can include layer 2 (L2) and/or layer 3 (L3) networks and devices.

The Internet is an example of a WAN that connects disparate networksthroughout the world, providing global communication between nodes onvarious networks. The nodes typically communicate over the network byexchanging discrete frames or packets of data according to predefinedprotocols, such as the Transmission Control Protocol/Internet Protocol(TCP/IP). In this context, a protocol can refer to a set of rulesdefining how the nodes interact with each other. Computer networks maybe further interconnected by an intermediate network node, such as arouter, to extend the effective “size” of each network.

Overlay networks generally allow virtual networks to be created andlayered over a physical network infrastructure. Overlay networkprotocols, such as Virtual Extensible LAN (VXLAN), NetworkVirtualization using Generic Routing Encapsulation (NVGRE), NetworkVirtualization Overlays (NVO3), and Stateless Transport Tunneling (STT),provide a traffic encapsulation scheme which allows network traffic tobe carried across L2 and L3 networks over a logical tunnel. Such logicaltunnels can be originated and terminated through virtual tunnel endpoints (VTEPs).

Moreover, overlay networks can include virtual segments, such as VXLANsegments in a VXLAN overlay network, which can include virtual L2 and/orL3 overlay networks over which virtual machines (VMs) communicate. Thevirtual segments can be identified through a virtual network identifier(VNI), such as a VXLAN network identifier, which can specificallyidentify an associated virtual segment or domain.

Network virtualization allows hardware and software resources to becombined in a virtual network. For example, network virtualization canallow multiple numbers of VMs to be attached to the physical network viarespective virtual LANs (VLANs). The VMs can be grouped according totheir respective VLAN, and can communicate with other VMs as well asother devices on the internal or external network.

Network segments, such as physical or virtual segments; networks;devices; ports; physical or logical links; and/or traffic in general canbe grouped into a bridge or flood domain. A bridge domain or flooddomain can represent a broadcast domain, such as an L2 broadcast domain.A bridge domain or flood domain can include a single subnet, but canalso include multiple subnets. Moreover, a bridge domain can beassociated with a bridge domain interface on a network device, such as aswitch. A bridge domain interface can be a logical interface whichsupports traffic between an L2 bridged network and an L3 routed network.In addition, a bridge domain interface can support internet protocol(IP) termination, VPN termination, address resolution handling, MACaddressing, etc. Both bridge domains and bridge domain interfaces can beidentified by a same index or identifier.

Furthermore, endpoint groups (EPGs) can be used in a network for mappingapplications to the network. In particular, EPGs can use a grouping ofapplication endpoints in a network to apply connectivity and policy tothe group of applications. EPGs can act as a container for buckets orcollections of applications, or application components, and tiers forimplementing forwarding and policy logic. EPGs also allow separation ofnetwork policy, security, and forwarding from addressing by insteadusing logical application boundaries.

Cloud computing can also be provided in one or more networks to providecomputing services using shared resources. Cloud computing can generallyinclude Internet-based computing in which computing resources aredynamically provisioned and allocated to client or user computers orother devices on-demand, from a collection of resources available viathe network (e.g., “the cloud”). Cloud computing resources, for example,can include any type of resource, such as computing, storage, andnetwork devices, virtual machines (VMs), etc. For instance, resourcesmay include service devices (firewalls, deep packet inspectors, trafficmonitors, load balancers, etc.), compute/processing devices (servers,CPU's, memory, brute force processing capability), storage devices(e.g., network attached storages, storage area network devices), etc. Inaddition, such resources may be used to support virtual networks,virtual machines (VM), databases, applications (Apps), etc.

Cloud computing resources may include a “private cloud,” a “publiccloud,” and/or a “hybrid cloud.” A “hybrid cloud” can be a cloudinfrastructure composed of two or more clouds that inter-operate orfederate through technology. In essence, a hybrid cloud is aninteraction between private and public clouds where a private cloudjoins a public cloud and utilizes public cloud resources in a secure andscalable manner. Cloud computing resources can also be provisioned viavirtual networks in an overlay network, such as a VXLAN.

FIG. 1 illustrates an exemplary network device 110 suitable forimplementing the present technology. Network device 110 includes amaster central processing unit (CPU) 162, interfaces 168, and a bus 115(e.g., a PCI bus). When acting under the control of appropriate softwareor firmware, the CPU 162 is responsible for executing packet management,error detection, and/or routing functions, such policy enforcement, forexample. The CPU 162 preferably accomplishes all these functions underthe control of software including an operating system and anyappropriate applications software. CPU 162 may include one or moreprocessors 163 such as a processor from the Motorola family ofmicroprocessors or the MIPS family of microprocessors. In an alternativeembodiment, processor 163 is specially designed hardware for controllingthe operations of router 110. In a specific embodiment, a memory 161(such as non-volatile RAM and/or ROM) also forms part of CPU 162.However, there are many different ways in which memory could be coupledto the system.

The interfaces 168 are typically provided as interface cards (sometimesreferred to as “line cards”). Generally, they control the sending andreceiving of data packets over the network and sometimes support otherperipherals used with the network device 110. Among the interfaces thatmay be provided are Ethernet interfaces, frame relay interfaces, cableinterfaces, DSL interfaces, token ring interfaces, and the like. Inaddition, various very high-speed interfaces may be provided such asfast token ring interfaces, wireless interfaces, Ethernet interfaces,Gigabit Ethernet interfaces, ATM interfaces, HSSI interfaces, POSinterfaces, FDDI interfaces and the like. Generally, these interfacesmay include ports appropriate for communication with the appropriatemedia. In some cases, they may also include an independent processorand, in some instances, volatile RAM. The independent processors maycontrol such communications intensive tasks as packet switching, mediacontrol, and management. By providing separate processors for thecommunications intensive tasks, these interfaces allow the mastermicroprocessor 162 to efficiently perform routing computations, networkdiagnostics, security functions, etc.

Although the system shown in FIG. 1 is one specific network device ofthe present technology, it is by no means the only network devicearchitecture on which the present technology can be implemented. Forexample, an architecture having a single processor that handlescommunications as well as routing computations, etc. is often used.Further, other types of interfaces and media could also be used with therouter.

Regardless of the network device's configuration, it may employ one ormore memories or memory modules (including memory 161) configured tostore program instructions for the general-purpose network operationsand mechanisms for roaming, route optimization and routing functionsdescribed herein. The program instructions may control the operation ofan operating system and/or one or more applications, for example. Thememory or memories may also be configured to store tables such asmobility binding, registration, and association tables, etc.

FIG. 2A, and FIG. 2B illustrate exemplary possible system embodiments.The more appropriate embodiment will be apparent to those of ordinaryskill in the art when practicing the present technology. Persons ofordinary skill in the art will also readily appreciate that other systemembodiments are possible.

FIG. 2A illustrates a conventional system bus computing systemarchitecture 200 wherein the components of the system are in electricalcommunication with each other using a bus 205. Exemplary system 200includes a processing unit (CPU or processor) 210 and a system bus 205that couples various system components including the system memory 215,such as read only memory (ROM) 220 and random access memory (RAM) 225,to the processor 210. The system 200 can include a cache of high-speedmemory connected directly with, in close proximity to, or integrated aspart of the processor 210. The system 200 can copy data from the memory215 and/or the storage device 230 to the cache 212 for quick access bythe processor 210. In this way, the cache can provide a performanceboost that avoids processor 210 delays while waiting for data. These andother modules can control or be configured to control the processor 210to perform various actions. Other system memory 215 may be available foruse as well. The memory 215 can include multiple different types ofmemory with different performance characteristics. The processor 210 caninclude any general purpose processor and a hardware module or softwaremodule, such as module 1 232, module 2 234, and module 3 236 stored instorage device 230, configured to control the processor 210 as well as aspecial-purpose processor where software instructions are incorporatedinto the actual processor design. The processor 210 may essentially be acompletely self-contained computing system, containing multiple cores orprocessors, a bus, memory controller, cache, etc. A multi-core processormay be symmetric or asymmetric.

To enable user interaction with the computing device 200, an inputdevice 245 can represent any number of input mechanisms, such as amicrophone for speech, a touch-sensitive screen for gesture or graphicalinput, keyboard, mouse, motion input, speech and so forth. An outputdevice 235 can also be one or more of a number of output mechanismsknown to those of skill in the art. In some instances, multimodalsystems can enable a user to provide multiple types of input tocommunicate with the computing device 200. The communications interface240 can generally govern and manage the user input and system output.There is no restriction on operating on any particular hardwarearrangement and therefore the basic features here may easily besubstituted for improved hardware or firmware arrangements as they aredeveloped.

Storage device 230 is a non-volatile memory and can be a hard disk orother types of computer readable media which can store data that areaccessible by a computer, such as magnetic cassettes, flash memorycards, solid state memory devices, digital versatile disks, cartridges,random access memories (RAMs) 225, read only memory (ROM) 220, andhybrids thereof.

The storage device 230 can include software modules 232, 234, 236 forcontrolling the processor 210. Other hardware or software modules arecontemplated. The storage device 230 can be connected to the system bus205. In one aspect, a hardware module that performs a particularfunction can include the software component stored in acomputer-readable medium in connection with the necessary hardwarecomponents, such as the processor 210, bus 205, display 235, and soforth, to carry out the function.

FIG. 2B illustrates a computer system 250 having a chipset architecturethat can be used in executing the described method and generating anddisplaying a graphical user interface (GUI). Computer system 250 is anexample of computer hardware, software, and firmware that can be used toimplement the disclosed technology. System 250 can include a processor255, representative of any number of physically and/or logicallydistinct resources capable of executing software, firmware, and hardwareconfigured to perform identified computations. Processor 255 cancommunicate with a chipset 260 that can control input to and output fromprocessor 255. In this example, chipset 260 outputs information tooutput 265, such as a display, and can read and write information tostorage device 270, which can include magnetic media, and solid statemedia, for example. Chipset 260 can also read data from and write datato RAM 275. A bridge 280 for interfacing with a variety of userinterface components 285 can be provided for interfacing with chipset260. Such user interface components 285 can include a keyboard, amicrophone, touch detection and processing circuitry, a pointing device,such as a mouse, and so on. In general, inputs to system 250 can comefrom any of a variety of sources, machine generated and/or humangenerated.

Chipset 260 can also interface with one or more communication interfaces290 that can have different physical interfaces. Such communicationinterfaces can include interfaces for wired and wireless local areanetworks, for broadband wireless networks, as well as personal areanetworks. Some applications of the methods for generating, displaying,and using the GUI disclosed herein can include receiving ordereddatasets over the physical interface or be generated by the machineitself by processor 255 analyzing data stored in storage 270 or 275.Further, the machine can receive inputs from a user via user interfacecomponents 285 and execute appropriate functions, such as browsingfunctions by interpreting these inputs using processor 255.

It can be appreciated that exemplary systems 200 and 250 can have morethan one processor 210 or be part of a group or cluster of computingdevices networked together to provide greater processing capability.

FIG. 3 illustrates a schematic block diagram of an example architecture300 for a network fabric 312. The network fabric 312 can include spineswitches 302 _(A), 302 _(B), . . . , 302 _(N) (collectively “302”)connected to leaf switches 304 _(A), 304 _(B), 304 _(C) . . . 304 _(N)(collectively “304”) in the network fabric 312.

Spine switches 302 can be L3 switches in the fabric 312. However, insome cases, the spine switches 302 can also, or otherwise, perform L2functionalities. Further, the spine switches 302 can support variouscapabilities, such as 40 or 10 Gbps Ethernet speeds. To this end, thespine switches 302 can include one or more 40 Gigabit Ethernet ports.Each port can also be split to support other speeds. For example, a 40Gigabit Ethernet port can be split into four 10 Gigabit Ethernet ports.

In some embodiments, one or more of the spine switches 302 can beconfigured to host a proxy function that performs a lookup of theendpoint address identifier to locator mapping in a mapping database onbehalf of leaf switches 304 that do not have such mapping. The proxyfunction can do this by parsing through the packet to the encapsulatedtenant packet to get to the destination locator address of the tenant.The spine switches 302 can then perform a lookup of their local mappingdatabase to determine the correct locator address of the packet andforward the packet to the locator address without changing certainfields in the header of the packet.

When a packet is received at a spine switch 302 _(i), the spine switch302 _(i) can first check if the destination locator address is a proxyaddress. If so, the spine switch 302 _(i) can perform the proxy functionas previously mentioned. If not, the spine switch 302 _(i) can look upthe locator in its forwarding table and forward the packet accordingly.

Spine switches 302 connect to leaf switches 304 in the fabric 312. Leafswitches 304 can include access ports (or non-fabric ports) and fabricports. Fabric ports can provide uplinks to the spine switches 302, whileaccess ports can provide connectivity for devices, hosts, endpoints,VMs, or external networks to the fabric 312.

Leaf switches 304 can reside at the edge of the fabric 312, and can thusrepresent the physical network edge. In some cases, the leaf switches304 can be top-of-rack (“ToR”) switches configured according to a ToRarchitecture. In other cases, the leaf switches 304 can be aggregationswitches in any particular topology, such as end-of-row (EoR) ormiddle-of-row (MoR) topologies. The leaf switches 304 can also representaggregation switches, for example.

The leaf switches 304 can be responsible for routing and/or bridging thetenant packets and applying network policies. In some cases, a leafswitch can perform one or more additional functions, such asimplementing a mapping cache, sending packets to the proxy function whenthere is a miss in the cache, encapsulate packets, enforce ingress oregress policies, etc.

Moreover, the leaf switches 304 can contain virtual switchingfunctionalities, such as a virtual tunnel endpoint (VTEP) function asexplained below in the discussion of VTEP 408 in FIG. 4. To this end,leaf switches 304 can connect the fabric 312 to an overlay network, suchas overlay network 400 illustrated in FIG. 4.

Network connectivity in the fabric 312 can flow through the leafswitches 304. Here, the leaf switches 304 can provide servers,resources, endpoints, external networks, or VMs access to the fabric312, and can connect the leaf switches 304 to each other. In some cases,the leaf switches 304 can connect EPGs to the fabric 312 and/or anyexternal networks. Each EPG can connect to the fabric 312 via one of theleaf switches 304, for example.

Endpoints 310A-E (collectively “310”) can connect to the fabric 312 vialeaf switches 304. For example, endpoints 310A and 310B can connectdirectly to leaf switch 304A, which can connect endpoints 310A and 310Bto the fabric 312 and/or any other one of the leaf switches 304.Similarly, endpoint 310E can connect directly to leaf switch 304C, whichcan connect endpoint 310E to the fabric 312 and/or any other of the leafswitches 304. On the other hand, endpoints 310C and 310D can connect toleaf switch 304B via L2 network 306. Similarly, the wide area network(WAN) can connect to the leaf switches 304C or 304D via L3 network 308.

Endpoints 310 can include any communication device, such as a computer,a server, a switch, a router, etc. In some cases, the endpoints 310 caninclude a server, hypervisor, or switch configured with a VTEPfunctionality which connects an overlay network, such as overlay network400 below, with the fabric 312. For example, in some cases, theendpoints 310 can represent one or more of the VTEPs 408A-D illustratedin FIG. 4. Here, the VTEPs 408A-D can connect to the fabric 312 via theleaf switches 304. The overlay network can host physical devices, suchas servers, applications, EPGs, virtual segments, virtual workloads,etc. In addition, the endpoints 310 can host virtual workload(s),clusters, and applications or services, which can connect with thefabric 312 or any other device or network, including an externalnetwork. For example, one or more endpoints 310 can host, or connect to,a cluster of load balancers or an EPG of various applications.

Although the fabric 312 is illustrated and described herein as anexample leaf-spine architecture, one of ordinary skill in the art willreadily recognize that the subject technology can be implemented basedon any network fabric, including any data center or cloud networkfabric. Indeed, other architectures, designs, infrastructures, andvariations are contemplated herein.

FIG. 4 illustrates an exemplary overlay network 400. Overlay network 400uses an overlay protocol, such as VXLAN, VGRE, VO3, or STT, toencapsulate traffic in L2 and/or L3 packets which can cross overlay L3boundaries in the network. As illustrated in FIG. 4, overlay network 400can include hosts 406A-D interconnected via network 402.

Network 402 can include a packet network, such as an IP network, forexample. Moreover, network 402 can connect the overlay network 400 withthe fabric 312 in FIG. 3. For example, VTEPs 408A-D can connect with theleaf switches 304 in the fabric 312 via network 402.

Hosts 406A-D include virtual tunnel end points (VTEP) 408A-D, which canbe virtual nodes or switches configured to encapsulate andde-encapsulate data traffic according to a specific overlay protocol ofthe network 400, for the various virtual network identifiers (VNIDs)410A-I. Moreover, hosts 406A-D can include servers containing a VTEPfunctionality, hypervisors, and physical switches, such as L3 switches,configured with a VTEP functionality. For example, hosts 406A and 406Bcan be physical switches configured to run VTEPs 408A-B. Here, hosts406A and 406B can be connected to servers 404A-D, which, in some cases,can include virtual workloads through VMs loaded on the servers, forexample.

In some embodiments, network 400 can be a VXLAN network, and VTEPs408A-D can be VXLAN tunnel end points (VTEP). However, as one ofordinary skill in the art will readily recognize, network 400 canrepresent any type of overlay or software-defined network, such asNVGRE, STT, or even overlay technologies yet to be invented.

The VNIDs can represent the segregated virtual networks in overlaynetwork 400. Each of the overlay tunnels (VTEPs 408A-D) can include oneor more VNIDs. For example, VTEP 408A can include VNIDs 1 and 2, VTEP408B can include VNIDs 1 and 2, VTEP 408C can include VNIDs 1 and 2, andVTEP 408D can include VNIDs 1-3. As one of ordinary skill in the artwill readily recognize, any particular VTEP can, in other embodiments,have numerous VNIDs, including more than the 3 VNIDs illustrated in FIG.4.

The traffic in overlay network 400 can be segregated logically accordingto specific VNIDs. This way, traffic intended for VNID 1 can be accessedby devices residing in VNID 1, while other devices residing in otherVNIDs (e.g., VNIDs 2 and 3) can be prevented from accessing suchtraffic. In other words, devices or endpoints connected to specificVNIDs can communicate with other devices or endpoints connected to thesame specific VNIDs, while traffic from separate VNIDs can be isolatedto prevent devices or endpoints in other specific VNIDs from accessingtraffic in different VNIDs.

Servers 404A-D and VMs 404E-I can connect to their respective VNID orvirtual segment, and communicate with other servers or VMs residing inthe same VNID or virtual segment. For example, server 404A cancommunicate with server 404C and VMs 404E and 404G because they allreside in the same VNID, viz., VNID 1. Similarly, server 404B cancommunicate with VMs 404F and 404H because they all reside in VNID 2.VMs 404E-I can host virtual workloads, which can include applicationworkloads, resources, and services, for example. However, in some cases,servers 404A-D can similarly host virtual workloads through VMs hostedon the servers 404A-D. Moreover, each of the servers 404A-D and VMs404E-I can represent a single server or VM, but can also representmultiple servers or VMs, such as a cluster of servers or VMs.

VTEPs 408A-D can encapsulate packets directed at the various VNIDs 1-3in the overlay network 400 according to the specific overlay protocolimplemented, such as VXLAN, so traffic can be properly transmitted tothe correct VNID and recipient(s). Moreover, when a switch, router, orother network device receives a packet to be transmitted to a recipientin the overlay network 400, it can analyze a routing table, such as alookup table, to determine where such packet needs to be transmitted sothe traffic reaches the appropriate recipient. For example, if VTEP 408Areceives a packet from endpoint 404B that is intended for endpoint 404H,VTEP 408A can analyze a routing table that maps the intended endpoint,endpoint 404H, to a specific switch that is configured to handlecommunications intended for endpoint 404H. VTEP 408A might not initiallyknow, when it receives the packet from endpoint 404B, that such packetshould be transmitted to VTEP 408D in order to reach endpoint 404H.Accordingly, by analyzing the routing table, VTEP 408A can lookupendpoint 404H, which is the intended recipient, and determine that thepacket should be transmitted to VTEP 408D, as specified in the routingtable based on endpoint-to-switch mappings or bindings, so the packetcan be transmitted to, and received by, endpoint 404H as expected.

However, continuing with the previous example, in many instances, VTEP408A may analyze the routing table and fail to find any bindings ormappings associated with the intended recipient, e.g., endpoint 404H.Here, the routing table may not yet have learned routing informationregarding endpoint 404H. In this scenario, the VTEP 408A may likelybroadcast or multicast the packet to ensure the proper switch associatedwith endpoint 404H can receive the packet and further route it toendpoint 404H.

In some cases, the routing table can be dynamically and continuouslymodified by removing unnecessary or stale entries and adding new ornecessary entries, in order to maintain the routing table up-to-date,accurate, and efficient, while reducing or limiting the size of thetable.

As one of ordinary skill in the art will readily recognize, the examplesand technologies provided above are simply for clarity and explanationpurposes, and can include many additional concepts and variations.

Depending on the desired implementation in the network 400, a variety ofnetworking and messaging protocols may be used, including but notlimited to TCP/IP, open systems interconnection (OSI), file transferprotocol (FTP), universal plug and play (UpnP), network file system(NFS), common internet file system (CIFS), AppleTalk etc. As would beappreciated by those skilled in the art, the network 400 illustrated inFIG. 4 is used for purposes of explanation, a network system may beimplemented with many variations, as appropriate, in the configurationof network platform in accordance with various embodiments of thepresent disclosure.

Having disclosed a brief introductory description of exemplary systemsand networks, the discussion now turns to reducing data transmissions ina VPN. Computing nodes in a VPN are tasked with transmitting a highnumber of data packets amongst each other for administrative purposes.For example, data packets, such as HELLO ACK packets, need to beperiodically sent to keep channels open between computing nodes.Likewise, probe packets are regularly sent to measure performancecharacteristics of a VPN tunnel. In large VPNs, the load fromtransmitting the desired number of these administrative data packets canoverload the router. To reduce the number of administrative data packetstransmitted in a VPN, computing nodes in the VPN can be configured toappend data included in an administrative data packet to client packetsscheduled to be delivered to another computing node in the VPN. Byappending this data to a client data packet, the number ofadministrative data packets transmitted amongst computing nodes can begreatly reduced or eliminated completely.

FIG. 5 illustrates a system for reducing data transmissions in a VPN. Asshown, system 500 includes computing node 502 and computing node 504 innetwork communication with each other in a VPN. Although system 500 isshown as only including two computing nodes, this is only for purposesof explanation and is not meant to be limiting. System 500 can includeany number of computing nodes in the VPN.

Computing node 502 and computing node 504 can communicate with eachother via a VPN tunnel established between computing node 502 andcomputing node 504. A VPN tunnel can be an established link betweencomputing nodes. Computing nodes 502 and 504 can use the VPN tunnel totransmit data packets back and forth. This can include client datapackets as well as administrative data packets. A client data packet canbe any data packet transmitted between computing nodes as a part ofservices or applications provided by the computing nodes, such as dataqueries, API calls, voice communications, etc. An administrative datapacket can be a data packet transmitted between computing nodes foradministrative purposes associated with providing or enhancingperformance of the VPN. For example, administrative data packets caninclude HELLO ACK packets that need to be periodically sent to keepchannels open between computing nodes or probe packets that areregularly sent between computing nodes to measure performancecharacteristics of a VPN tunnel.

To reduce the number of administrative data packets transmitted betweencomputing nodes, computing nodes 502 and 504 can be configured to appendthe data included in the administrative data packets to client datapackets scheduled for transmission between computing nodes 502 and 504.Many client data packets leave a portion of unused bytes that can beused to accommodate the appended data. For example, data packetstransmitted in a VPN can have a capacity of 1500 bytes and a client datapacket, such as a standard voice communication packet, can utilize only800 of the 1500 bytes. Accordingly, the client data packet can include700 unused bytes that can be utilized to store the appended data thatwould normally be included in an administrative data packet (e.g., aHELLO ACK or probe packet).

Prior to transmitting a client data packet, computing nodes 502 and 504can be configured to append the client data packet with data that wouldnormally be transmitted as a separate administrative data packet. Toensure that each data packet includes enough unused bytes for theappended data, the Maximum Transmission Unit (MTU) for a VPN tunnel canbe reduced by an amount sufficient to ensure that at least a thresholdamount of unused bytes remain for the appended data.

Computing nodes 502 and 504 can append a client data packet with dataincluded in multiple types of administrative data packets. For example,a client data packet can be appended with the data that would beincluded in both a separate HELLO ACK and probe packet. In someembodiments, computing nodes 502 and 504 can append data to all clientdata packets that are scheduled for transmission to other computingnodes. Alternatively, computing nodes 502 and 504 can append client datapackets as needed to satisfy a desired transmission threshold ofadministrative data packets. For example, computing nodes 502 and 504can be configured to transmit a desired transmission threshold number ofadministrative data packets within a specified time period. In this typeof embodiment, computing nodes 502 and 504 can be configured to appendall client data packets until the threshold is met for each specifiedtime period, such as every 5 seconds.

In some embodiments, computing nodes 502 and 504 can utilize a hybridapproach of appending client data packets and transmitting separateadministrative data packets to satisfy a desired transmission threshold.For example, computing nodes 502 and 504 can supplement the use ofappending client data packets by transmitting separate administrativedata packets to satisfy the desired transmission threshold whenappending client data packets alone would not be sufficient to satisfythe desired transmission threshold.

FIG. 6 illustrates computing nodes appending client data packets tomeasure performance characteristics of a VPN tunnel. Computing nodes 602and 604 can append client data packets to track the transmission time ofthe data packets using various uplink ports and thereby determine theperformance level of the corresponding VPN tunnels.

As shown, computing node 602 can transmit client data packet 606 tocomputing node 604 at time t1. Client data packet 606 can be appendedwith a unique identifier that corresponds to a transmission recordmaintained by computing node 602. For example, prior to transmittingclient data packet 606, computing node 602 can append client data packet606 with the unique identifier. The unique identifier can be any type ofunique string, number, combination of characters, etc. The transmissionrecord can include the unique identifier as well as a time stamp valuefor client data packet 606 that indicates the time (i.e., t1) at whichclient data packet 606 was transmitted by computing node 602 tocomputing node 604. After appending data packet 606 to include theunique identifier, computing node 602 can transmit data packet 606 tocomputing node 604 via a first uplink port of computing node 602. Thefirst uplink port can be providing a VPN tunnel between computing node602 and computing node 604.

Computing node 604 can receive client data packet 606 at time t2.Computing node 604 can transmit client data packet 608 to computing node602 at time t3. Prior to transmitting client data packet 608, computingnode 604 can append client data packet 608 with the unique identifier aswell as a delta time indicating the amount of elapsed time betweencomputing node 604 receiving client data packet 608 and computing node604 transmitting client data packet 608 (i.e., the elapsed time betweent2 to t3).

Computing node 602 can receive client data packet 608 at time t4.Computing node 602 can use the unique identifier included in client datapacket 608 to identify the corresponding transmission record and gatherthe time stamp value for client data packet 606. Computing node 602 canuse the time stamp value for client data packet 606, the delta timeincluded in client data packet 608 and the time at which client datapacket 608 was received (i.e., t4) to determine a total response timefor the VPN tunnel. The total response time can indicate the amount oftime elapsed transmitting data packets between computing nodes 602 and604 using the VPN tunnel. For example, to calculate the total responsetime, computing node 602 can calculate a total response time spanningfrom t1 to t4, and then subtract the delta time.

Computing node 602 can use the total response time to determine aperformance level of the VPN tunnel. Computing node 602 can repeat thisprocess with multiple VPN tunnels and then prioritize use of the VPNtunnels based on their determined performance levels.

FIG. 7 illustrates an example method for reducing data transmissions ina virtual private network. It should be understood that there can beadditional, fewer, or alternative steps performed in similar oralternative orders, or in parallel, within the scope of the variousembodiments unless otherwise stated.

At step 702, a source node can append a first unique identifier to afirst outbound client packet scheduled to be transmitted from the sourcenode to a first recipient node. The outbound client packet can be aclient data packet transmitted between the computing nodes as a part ofservices or applications provided by the computing nodes, such as dataqueries, API calls, voice communications, etc. The first uniqueidentifier appended to the first outbound client packet can be data thatwould traditionally be transmitted as a separate administrative datapacket. An administrative data packet can be a data packet transmittedbetween computing nodes for administrative purposes associated withproviding or enhancing performance of the VPN network. For example, theunique identifier appended to the first outbound client packet can bedata that would be included in a probe packet transmitted betweencomputing nodes to measure performance characteristics of a VPN tunnel.

The number of data transmission in the VPN can be greatly reduced byappending the first unique identifier to the first outbound clientpacket rather that transmitting the first unique identifier as aseparate administrative data packet.

At step 704, the source node can transmit the first outbound clientpacket to the first recipient node via a first port of the source node.The first port can be an uplink port used to provide a first VPN tunnelbetween the source node and the first recipient node. Prior to appendingthe first outbound client packet, a Maximum Transmission Unit (MTU) forthe first VPN tunnel can be reduced to ensure that at least a thresholdamount of unused bytes are available in data packets transmitted via thefirst VPN tunnel for appended data

At step 706, the source node can create a first transmission recordincluding the first unique identifier, a time stamp of the firstoutbound client packet, and an identifier for the first port. The timestamp value of the first outbound client packet can indicate a time atwhich the first outbound client packet was transmitted by the sourcenode to the first recipient node.

At step 708, the source node can receive a first inbound client packetfrom the first recipient node. The first inbound client packet can beappended with the first unique identifier and a first delta timeindicating an amount of elapsed time between the first recipient nodereceiving the first outbound client packet and the first recipient nodetransmitting the first inbound client packet. After receiving the firstinbound data packet, the source node can identify the first transmissionrecord based on the first unique identifier included in the firstinbound data packet.

At step 710, the source node can determine a performance level of afirst Virtual Private Network (VPN) tunnel provided by the first portbased on the time stamp value of the first outbound client packet, thefirst delta time, and a time stamp value of the first inbound clientpacket. The time stamp value of the first inbound client packet canindicate a time at which the first inbound client packet was received bythe source node.

To determine the performance level of the first VPN tunnel, the sourcenode can determine a total response time for the first VPN tunnelspanning from the time stamp value of the first outbound data packet tothe time stamp value of the first inbound data packet. The source nodecan then subtract the first delta time from the total response time todetermine an actual transmission time for the first VPN tunnel. Thesource node can determine the performance level of the first VPN tunnelbased on the actual transmission time for the first VPN tunnel. Forexample, the source node can compare the actual transmission time to oneor more a threshold transmission times to determine the performancelevel of the VPN tunnel.

In some embodiments, the source node can compare the performance ofseparate VPN tunnels to determine which VPN tunnel is performing better.For example, the source node can determine the performance level of asecond VPN tunnel provided by a second port of the source node. Thesource node can then compare the performance levels of the first VPNtunnel and the second VPN tunnel. If the source node determines that,based on the performance level of the first VPN tunnel and theperformance level of the second VPN tunnel, the first VPN tunnel isperforming better than the second VPN tunnel, the source node candesignate the first port as a preferred port. As a result, the firstport and thereby the first VPN tunnel can be given priority whentransmitting data packets, thereby decreasing networking latency.

As one of ordinary skill in the art will readily recognize, the examplesand technologies provided above are simply for clarity and explanationpurposes, and can include many additional concepts and variations.

For clarity of explanation, in some instances the present technology maybe presented as including individual functional blocks includingfunctional blocks comprising devices, device components, steps orroutines in a method embodied in software, or combinations of hardwareand software.

In some embodiments the computer-readable storage devices, mediums, andmemories can include a cable or wireless signal containing a bit streamand the like. However, when mentioned, non-transitory computer-readablestorage media expressly exclude media such as energy, carrier signals,electromagnetic waves, and signals per se.

Methods according to the above-described examples can be implementedusing computer-executable instructions that are stored or otherwiseavailable from computer readable media. Such instructions can comprise,for example, instructions and data which cause or otherwise configure ageneral purpose computer, special purpose computer, or special purposeprocessing device to perform a certain function or group of functions.Portions of computer resources used can be accessible over a network.The computer executable instructions may be, for example, binaries,intermediate format instructions such as assembly language, firmware, orsource code. Examples of computer-readable media that may be used tostore instructions, information used, and/or information created duringmethods according to described examples include magnetic or opticaldisks, flash memory, USB devices provided with non-volatile memory,networked storage devices, and so on.

Devices implementing methods according to these disclosures can comprisehardware, firmware and/or software, and can take any of a variety ofform factors. Typical examples of such form factors include laptops,smart phones, small form factor personal computers, personal digitalassistants, rackmount devices, standalone devices, and so on.Functionality described herein also can be embodied in peripherals oradd-in cards. Such functionality can also be implemented on a circuitboard among different chips or different processes executing in a singledevice, by way of further example.

The instructions, media for conveying such instructions, computingresources for executing them, and other structures for supporting suchcomputing resources are means for providing the functions described inthese disclosures.

Although a variety of examples and other information was used to explainaspects within the scope of the appended claims, no limitation of theclaims should be implied based on particular features or arrangements insuch examples, as one of ordinary skill would be able to use theseexamples to derive a wide variety of implementations. Further andalthough some subject matter may have been described in languagespecific to examples of structural features and/or method steps, it isto be understood that the subject matter defined in the appended claimsis not necessarily limited to these described features or acts. Forexample, such functionality can be distributed differently or performedin components other than those identified herein. Rather, the describedfeatures and steps are disclosed as examples of components of systemsand methods within the scope of the appended claims. Moreover, claimlanguage reciting “at least one of” a set indicates that one member ofthe set or multiple members of the set satisfy the claim.

For clarity of explanation, in some instances the present technology maybe presented as including individual functional blocks includingfunctional blocks comprising devices, device components, steps orroutines in a method embodied in software, or combinations of hardwareand software.

Note that in certain example implementations, the optimization and/orplacement functions outlined herein may be implemented by logic encodedin one or more tangible, non-transitory media (e.g., embedded logicprovided in an application specific integrated circuit [ASIC], digitalsignal processor [DSP] instructions, software [potentially inclusive ofobject code and source code] to be executed by a processor, or othersimilar machine, etc.). The computer-readable storage devices, mediums,and memories can include a cable or wireless signal containing a bitstream and the like. However, when mentioned, non-transitorycomputer-readable storage media expressly exclude media such as energy,carrier signals, electromagnetic waves, and signals per se.

Methods according to the above-described examples can be implementedusing computer-executable instructions that are stored or otherwiseavailable from computer readable media. Such instructions can comprise,for example, instructions and data which cause or otherwise configure ageneral purpose computer, special purpose computer, or special purposeprocessing device to perform a certain function or group of functions.Portions of computer resources used can be accessible over a network.The computer executable instructions may be, for example, binaries,intermediate format instructions such as assembly language, firmware, orsource code. Examples of computer-readable media that may be used tostore instructions, information used, and/or information created duringmethods according to described examples include magnetic or opticaldisks, flash memory, USB devices provided with non-volatile memory,networked storage devices, and so on.

Devices implementing methods according to these disclosures can comprisehardware, firmware and/or software, and can take any of a variety ofform factors. Typical examples of such form factors include laptops,smart phones, small form factor personal computers, personal digitalassistants, and so on. Functionality described herein also can beembodied in peripherals or add-in cards. Such functionality can also beimplemented on a circuit board among different chips or differentprocesses executing in a single device, by way of further example.

The instructions, media for conveying such instructions, computingresources for executing them, and other structures for supporting suchcomputing resources are means for providing the functions described inthese disclosures.

Although a variety of examples and other information was used to explainaspects within the scope of the appended claims, no limitation of theclaims should be implied based on particular features or arrangements insuch examples, as one of ordinary skill would be able to use theseexamples to derive a wide variety of implementations. Further andalthough some subject matter may have been described in languagespecific to examples of structural features and/or method steps, it isto be understood that the subject matter defined in the appended claimsis not necessarily limited to these described features or acts. Forexample, such functionality can be distributed differently or performedin components other than those identified herein. Rather, the describedfeatures and steps are disclosed as examples of components of systemsand methods within the scope of the appended claims.

1. A method comprising: appending, by a source node, a first unique identifier to a first outbound client packet scheduled to be transmitted from the source node to a first recipient node; after appending the first unique identifier to the first outbound client packet: transmitting, by the source node, the first outbound client packet to the first recipient node via a first port of the source node, and creating a first transmission record including the first unique identifier, a time stamp of the first outbound client packet, and an identifier for the first port, wherein the time stamp value of the first outbound client packet indicates a time at which the first outbound client packet was transmitted by the source node to the first recipient node; receiving, by the source node, a first inbound client packet from the first recipient node, the first inbound client packet appended with the first unique identifier and a first delta time indicating an amount of elapsed time between the first recipient node receiving the first outbound client packet and the first recipient node transmitting the first inbound client packet; and determining, by the source node, a performance level of a first Virtual Private Network (VPN) tunnel provided by the first port based on the time stamp value of the first outbound client packet, the first delta time, and a time stamp value of the first inbound client packet, wherein the time stamp value of the first inbound client packet indicates a time at which the first inbound client packet was received by the source node.
 2. The method of claim 1, further comprising: appending a second unique identifier to a second outbound client packet scheduled to be transmitted from the source node to a second recipient node; after appending the second unique identifier to the second outbound client packet: transmitting the second outbound client packet to the second recipient node via a second port of the source node, and creating a second transmission record including the second unique identifier, a transmission time stamp of the second outbound client packet, and an identifier for the second port, wherein the transmission time stamp of the second outbound client packet indicates a time at which the second outbound client packet was transmitted by the source node to the second recipient node; receiving a second inbound client packet from the second recipient node, the second inbound client packet appended with the second unique identifier and a second delta time indicating an amount of elapsed time between the second recipient node receiving the second outbound client packet and the second recipient node transmitting the second inbound client packet; and determining a performance level of a second VPN tunnel provided by the second port based on the transmission time of the second outbound client packet, the second delta time, and a time stamp value of the second inbound client packet, wherein the time stamp value of the second inbound client packet indicates a time at which the second inbound client packet was received by the source node.
 3. The method of claim 2, further comprising: determining, based on the performance level of the first VPN tunnel and the performance level of the second VPN tunnel, that the first VPN tunnel is performing better than the second VPN tunnel; and in response to determining that the first VPN tunnel is performing better than the second VPN tunnel, designating the first port as a preferred port.
 4. The method of claim 1, wherein determining a performance level of the first VPN tunnel comprises: determining a total response time for the first VPN tunnel spanning from the time stamp value of the first outbound client packet to the time stamp value of the first inbound client packet; subtracting the first delta time from the total response time, yielding an actual transmission time for the first VPN tunnel; and determining the performance level of the first VPN tunnel based on the actual transmission time for the first VPN tunnel.
 5. The method of claim 1, further comprising: after receiving the first inbound client packet, identifying the first transmission record based on the first unique identifier included in the first inbound client packet.
 6. The method of claim 1, further comprising: prior to appending the first outbound client packet, reducing a Maximum Transmission Unit (MTU) for the first VPN tunnel to ensure that at least a threshold amount of unused bytes are available in data packets transmitted via the first VPN tunnel for appended data.
 7. The method of claim 2, wherein the first recipient node is different than the second recipient node.
 8. A source node comprising: one or more computer processors; and a memory storing instructions that, when executed by the one or more computer processors, cause the source node to: append a first unique identifier to a first outbound client packet scheduled to be transmitted from the source node to a first recipient node; after appending the first unique identifier to the first outbound client packet: transmit the first outbound client packet to the first recipient node via a first port of the source node, and create a first transmission record including the first unique identifier, a time stamp of the first outbound client packet, and an identifier for the first port, wherein the time stamp value of the first outbound client packet indicates a time at which the first outbound client packet was transmitted by the source node to the first recipient node; receive a first inbound client packet from the first recipient node, the first inbound client packet appended with the first unique identifier and a first delta time indicating an amount of elapsed time between the first recipient node receiving the first outbound client packet and the first recipient node transmitting the first inbound client packet; and determine a performance level of a first Virtual Private Network (VPN) tunnel provided by the first port based on the time stamp value of the first outbound client packet, the first delta time, and a time stamp value of the first inbound client packet, wherein the time stamp value of the first inbound client packet indicates a time at which the first inbound client packet was received by the source node.
 9. The source node of claim 8, wherein the instructions further cause the source node to: append a second unique identifier to a second outbound client packet scheduled to be transmitted from the source node to a second recipient node; after appending the second unique identifier to the second outbound client packet: transmit the second outbound client packet to the second recipient node via a second port of the source node, and create a second transmission record including the second unique identifier, a transmission time stamp of the second outbound client packet, and an identifier for the second port, wherein the transmission time stamp of the second outbound client packet indicates a time at which the second outbound client packet was transmitted by the source node to the second recipient node; receive a second inbound client packet from the second recipient node, the second inbound client packet appended with the second unique identifier and a second delta time indicating an amount of elapsed time between the second recipient node receiving the second outbound client packet and the second recipient node transmitting the second inbound client packet; and determine a performance level of a second VPN tunnel provided by the second port based on the transmission time of the second outbound client packet, the second delta time, and a time stamp value of the second inbound client packet, wherein the time stamp value of the second inbound client packet indicates a time at which the second inbound client packet was received by the source node.
 10. The source node of claim 9, wherein the instructions further cause the source node to: determine, based on the performance level of the first VPN tunnel and the performance level of the second VPN tunnel, that the first VPN tunnel is performing better than the second VPN tunnel; and in response to determining that the first VPN tunnel is performing better than the second VPN tunnel, designate the first port as a preferred port.
 11. The source node of claim 8, wherein determining a performance level of the first VPN tunnel comprises: determining a total response time for the first VPN tunnel spanning from the time stamp value of the first outbound client packet to the time stamp value of the first inbound client packet; subtracting the first delta time from the total response time, yielding an actual transmission time for the first VPN tunnel; and determining the performance level of the first VPN tunnel based on the actual transmission time for the first VPN tunnel.
 12. The source node of claim 8, wherein the instructions further cause the source node to: after receiving the first inbound client packet, identify the first transmission record based on the first unique identifier included in the first inbound client packet.
 13. The source node of claim 8, wherein the instructions further cause the source node to: prior to appending the first outbound client packet, reduce a Maximum Transmission Unit (MTU) for the first VPN tunnel to ensure that at least a threshold amount of unused bytes are available in data packets transmitted via the first VPN tunnel for appended data.
 14. The source node of claim 9, wherein the first recipient node is different than the second recipient node.
 15. A non-transitory computer-readable medium storing instructions that, when executed by the one or more computer processors, cause the source node to: append a first unique identifier to a first outbound client packet scheduled to be transmitted from the source node to a first recipient node; after appending the first unique identifier to the first outbound client packet: transmit the first outbound client packet to the first recipient node via a first port of the source node, and create a first transmission record including the first unique identifier, a time stamp of the first outbound client packet, and an identifier for the first port, wherein the time stamp value of the first outbound client packet indicates a time at which the first outbound client packet was transmitted by the source node to the first recipient node; receive a first inbound client packet from the first recipient node, the first inbound client packet appended with the first unique identifier and a first delta time indicating an amount of elapsed time between the first recipient node receiving the first outbound client packet and the first recipient node transmitting the first inbound client packet; and determine a performance level of a first Virtual Private Network (VPN) tunnel provided by the first port based on the time stamp value of the first outbound client packet, the first delta time, and a time stamp value of the first inbound client packet, wherein the time stamp value of the first inbound client packet indicates a time at which the first inbound client packet was received by the source node.
 16. The non-transitory computer-readable medium of claim 15, wherein the instructions further cause the source node to: append a second unique identifier to a second outbound client packet scheduled to be transmitted from the source node to a second recipient node; after appending the second unique identifier to the second outbound client packet: transmit the second outbound client packet to the second recipient node via a second port of the source node, and create a second transmission record including the second unique identifier, a transmission time stamp of the second outbound client packet, and an identifier for the second port, wherein the transmission time stamp of the second outbound client packet indicates a time at which the second outbound client packet was transmitted by the source node to the second recipient node; receive a second inbound client packet from the second recipient node, the second inbound client packet appended with the second unique identifier and a second delta time indicating an amount of elapsed time between the second recipient node receiving the second outbound client packet and the second recipient node transmitting the second inbound client packet; and determine a performance level of a second VPN tunnel provided by the second port based on the transmission time of the second outbound client packet, the second delta time, and a time stamp value of the second inbound client packet, wherein the time stamp value of the second inbound client packet indicates a time at which the second inbound client packet was received by the source node.
 17. The non-transitory computer-readable medium of claim 16, wherein the instructions further cause the source node to: determine, based on the performance level of the first VPN tunnel and the performance level of the second VPN tunnel, that the first VPN tunnel is performing better than the second VPN tunnel; and in response to determining that the first VPN tunnel is performing better than the second VPN tunnel, designate the first port as a preferred port.
 18. The non-transitory computer-readable medium of claim 15, wherein determining a performance level of the first VPN tunnel comprises: determining a total response time for the first VPN tunnel spanning from the time stamp value of the first outbound client packet to the time stamp value of the first inbound client packet; subtracting the first delta time from the total response time, yielding an actual transmission time for the first VPN tunnel; and determining the performance level of the first VPN tunnel based on the actual transmission time for the first VPN tunnel.
 19. The non-transitory computer-readable medium of claim 15, wherein the instructions further cause the source node to: after receiving the first inbound client packet, identify the first transmission record based on the first unique identifier included in the first inbound client packet.
 20. The non-transitory computer-readable medium of claim 15, wherein the instructions further cause the source node to: prior to appending the first outbound client packet, reduce a Maximum Transmission Unit (MTU) for the first VPN tunnel to ensure that at least a threshold amount of unused bytes are available in data packets transmitted via the first VPN tunnel for appended data. 